1. Field of the Invention
This invention generally relates to an image forming device and a host terminal connected to the image forming device. More particularly, this invention relates to an image forming device which performs an image output process based on an image output request from a specific user when one or a plurality of host terminals are connected to the image forming device.
2. Description of the Related Art
In a recent office environment, an image forming device which is shared by a plurality of users is connected to a network. If the users try to output image data by using the image forming device simultaneously, after a printing job of a first user is completed, a printing job of a second user is subsequently performed. In order to carry out this operation without delay, the image forming device has to receive the second user's print data during the first user's printing job. For this purpose, the image forming device requires a memory unit which holds the second user's print data at this time.
In addition, in the case of the above-mentioned the image forming device, the respective printed results of the first user and the second user are outputted using the same device, and there is a problem that one user is able to easily see the printed result of another user. If the printed result contains confidential data, the leakage of the confidential data to an outsider tends to arise in this case.
To obviate the problem, an image forming device having a confidential output function has been proposed. When this confidential output function is used, each user is requested, prior to starting image output operation, to input an identification data, such as a password, which is set up at the time of printing, and only a document image the printing of which is requested by the user together with the identification data is outputted by the image forming device.
FIG. 1 shows an example of the printing procedure performed by the image forming device having the confidential output function.
Upon start of the procedure of FIG. 1, in step S101, the user inputs the user-identification (ID) data for identifying the user, to a host terminal 1 (which is a personal computer (PC)).
In step S102, the host terminal 1 transmits a printing request for execution of a print job to an image forming device 2 together with the user-identification data, or separately from the transmission of the user-identification data to the image forming device 2.
In step S103, the image forming device 2 stores the user-identification data received from the host terminal 1, into a memory unit provided in the image forming device 2.
When the image forming device 2 at this time is in a print enabled state, the image forming device 2 transmits a notice of print enabled state to the host terminal 1.
After the notice of print enabled state is received from the image forming device 2, the host terminal 1 starts transmission of print data to the image forming device 2 in step S104.
After the transmission of print data is completed in step S105, the host terminal 1 is in a waiting state in which receiving of a printed result from the image forming device 2 is awaited.
In step S106, the image forming device 2 stores the print data received from the host terminal 1, into the memory unit.
Subsequently, in step S107, the user inputs the user-identification data for identifying the user, to the image forming device 2 through the operation panel.
In step S108, the user-identification data received from the host terminal 1 and stored in step S103 is compared with the user-identification data inputted in step S107.
When a match of these user-identification data occurs as a result of comparison, the image forming device 2 starts printing of the print data stored in the memory unit in step S109.
After printing is completed in step S100, the image forming device 2 transmits a notice of end of printing to the host terminal 1.
Finally, in step S111, the host terminal 1 finishes the printing operation in response to the notice of end of printing received from the image forming device 2.
Thus, using the confidential output function of the conventional image forming device makes it possible to eliminate the above problem that the printed result may be seen by another user other than the user who has performed the printing request.
However, as is apparent from the above-described printing procedure, it is necessary that the conventional image forming device having the confidential output function continuously holds the received print data until an image output is requested by the user with the input of the user-identification data. Thus, there is a problem that the conventional image forming device must have a mass storage device, in order to allow a large number of users who share the image forming device to utilize the image forming device.
To obviate the above problem, Japanese Laid-Open Patent Application No. 2001-051811 discloses a printing device having an improved function. This printing device is provided with a memory device, and the print data received from a PC client (host terminal) are stored in the memory device. Thereafter, printing operation is performed by the printing device in response to a printing request received from the user. In order to use efficiently the printing device which is shared by a large number of users, the printing device is provided so that the unused areas of the memory device may be expanded by lowering the resolution of image data stored in the memory device.
However, even if the unused areas of the memory device (e.g., a HDD) provided in the image forming device (disclosed in Japanese Laid-Open Patent Application No. 2001-051811) can be expanded by lowering the resolution of image data stored in the memory device, the memory device has a limited storage capacity. When the number of host terminals connected to the image forming device is further increased, or when the number of users who share the image forming device is further increased, there is a restriction as to the expansion of the unused areas of the memory device. And there is a problem that the necessity of large storage capacity of the memory device cannot be eliminated. Moreover, the manufacturing cost of the image forming device will be increased in association with an increase of the storage capacity of the memory device.